Not sure about outboard bearings being 'bomb proof'. I suppose it depends on what you are comparing them to, but my old square-taper bottom bracket still spins beautifully and it last for many more years.

THe only bomb proof bb standards were the good old square taper and all the others shimano has developed (octalink, hollowtech2, press fit bb92). All the rest fail, with the exception of sram gpx and maybe bb30 press fit.

Looking forward to see the next shimano 105. It's a pity than in shimano you have to go down to the 105 to have a full black groupset. Sram and campy do it much better. This ambiguous grey is so so... But not bad for a carbon frame though...

^ this. If 105 is black and has the 4-arm crank I will be seriously tempted.....I don't really NEED 11 speed.

Lol... I have ten speeds and i think i would be pretty fine with 8. Not 6, not seven, but 8 would be perfectly fine for me. I won't be using 11 though, I will buy old stock from 10 speed and wait for 12. I always do this, otherwise my wallet gets too light and i feel so guilty...

For tubing, a general rule is you don't want the wall thickness to go beyond 1/50th the diameter (or radius, I can't remember...). A steel spindle at 30mm would require too thin a wall to be of equal weight to an aluminum one. you would get buckling.Shimano used to make some aluminum 24mm spindles. It was on the first 5600 and 6600 cranks. When they came out with their half-upgrade 6600g, they moved it up to steel.

shimano does not do BB30 because they do not believe that BB30 is a superior standard. they have argued this before, and as a mechanical engineer, their argument does have merits. BB30 gives you a tiny and, to a human, imperceptible increase in stiffness for much much higher complexity in maintaining the system. you get smaller Q factor, yes, but that is not a good enough reason IMO. it is, technically more robust to the elements than outboard bearings, but they are a PAIN to replace if something goes wrong. outboard cransk are much easier to replace, more versatile, and less likely to damage your frame on installation. same goes for PF30, and to an extent, BB86 and BBright as well. shimano will also make less money. so I DO see why they would not support BB30.

BB30 is popular among frame manufacturers because it saves them money. it's much faster and cheaper to purchase an OE spec bearing and press it into the fram than having to machine out steel threaded inserts and bond them into frames. it's a simple case of frame manufacturers versus shimano here. but shimano is sticking to their guns and as the major industry player, they have evrey right and clout to do so.

the 4 arm design may LOOK weird, but it offers tangible engineering benefits. the 4 arm design has been on shimano MTB cranks for awhile now. 4 arms are lighter than 5 arms, and shimano claim that the crank still retains the same level of stiffness. in addition, the new 4 arm design makes 110 or 130mm BCD pointless. you can put a 50-34 on that crank. you can also put a 53-39 on the very same crank. this is a game changer. cuts down inventory that stores need to hold ( you don't neeed to carry both compact and standard cranks anymore.) it also streamlines manufacturing. these savings may eventuaklly be passed down to the consumer if enough people follow their 4 arm standard and make chainrings for 4 arm cranks. ( shimano chainrigns are great but exoensive.) the problem here is that most other crank or chainring manufacturers are 5 arm, so they are trying to revolutionize the game here. My feeling is that this is a real game changer. once you get used to the 4 arm design, it actually looks pretty cool.

the new crank is certainly an impressive bit of techy kit and I'll be trying to get my hands on one as soon as ultegra 6800 comes out.

4 arms road crankset, for compact and no compact is a great idea if you use shimano expensive hollow chainrings. Those chainrings are very stiff, and they are extremely expensive to produce for shimano, imagine how expensive they would be for another manufacturer who won't produce a few millions of them... Quite a big shit is what i would call these new cranks. Not only that they are ugly as hell, but that they make 3rd party rings kind of impossible.

It's amazing to me how some people has such a little engineering manufacturing knowledge, and still write these pointless opinions with no reservations... welcome to planet earth i guess...

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